Add mongodb support to gutterball

Testing is still a bit of a PITA at the moment, and require a live DB -- ugh. Played with Fongo, but there are some features of the mongodb-java-driver that are not currently supported.

TODO: Find a way to isolate these tests as integration tests.

NOTE: Some tests currently require a mongodb setup in order for them to be run.
Is it proper to expose ```DBCursor```? Seems like this would be a ```List<xxx>```